1. Field of the Invention
The present invention generally relates to a stage device, an exposure apparatus using the same and a device manufacturing method, wherein the exposure apparatus is preferably used in a lithography process for manufacturing micro-devices.
2. Description of the Related Art
In a lithography process for manufacturing micro-devices (e.g., semiconductors), two types of exposure apparatuses are known. One is a step-and-repeat type (so-called a stepper) and the other is a step-and-scan type (so-called a scanner or a scanning type exposure apparatus).
The former type uses a step-and-repeat sequence for transferring stepwise a pattern of an original (e.g., a reticle or a mask) onto a substrate (e.g., a semiconductor wafer or a glass or silicon substrate). In that sequence, the whole pattern of the original is illuminated and is projected onto one of a plurality of exposure regions on the substrate through a projection optical system, while the original and the substrate are maintained stationary. Next, the substrate is moved stepwise to change the exposure region, and then exposure is repeated in the same manner.
On the other hand, the latter type uses a step-and-scan sequence. In that sequence, an original pattern is illuminated with a slit-like beam and a portion of the pattern is projected onto one of a plurality of exposure regions on a substrate, while both the original and the substrate are scanningly moved. Next, the substrate is moved stepwise to change the exposure region, and then exposure is repeated in the same manner.
The step-and-scan type exposure apparatus seems to have become the mainstream, at least for the near future, for the reason that it has a potential for high exposure performance in terms of an increase in transferring precision and field size.
These types of exposure apparatuses include stage devices (e.g., a wafer stage or a reticle stage) for moving and positioning the wafer or the reticle rapidly. However, when the stage moves with a high rate of acceleration (positive or negative), a reaction of an inertial force occurs and this can cause vibration of not only a base which supports the stage, but also a floor which supports the whole exposure apparatus. This vibration might cause a natural oscillation of the mechanical system of the exposure apparatus and that disturbs the positioning of the stage.
The acceleration of the stage movement has recently been increasing more and more as a result of progress in the throughput (processing speed) in an exposure operation. In the step-and-scan type exposure apparatus, the maximum acceleration has reached as much as 4 G (for the reticle stage) and 1 G (for the wafer stage), for example. Furthermore, due to an increase in the original size and the substrate size, the stage mass has been increasing. For these reasons, a driving force, as defined by the stage mass multiplied by the acceleration, has become enormous, and that means the reaction of the driving force has also become enormous. Consequently, the vibration of the floor as described above has become an actual challenge to be solved.